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OCR Chemistry F322~ 4th June 2013~ AS Chemistry

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Original post by Joew1995

I'm also wondering about the cracking question on the first page. C15H32 can crack to form anything really can't it? That mark scheme showed a compound with C5 and a compound with C10 but I put propane and 4 molecules of propene i think, which balanced correctly.

Do we get the mark for putting any balanced equation or does it have to be C15H32? The question didn't state any specific products being produced.

You could put any products as long as the C's and H's add up to C15H32 and as long as you produced an alkene and an alkane

Reply 4121

V__005

Original post by Ché.

Yeah...
Roughly, that's the insight of the question.
The concept is basically asking you to mention that it is randomly broken - no cracking programming is available; this means no one controls this process.

It totally implies the answer.., 1/1.

Out of context to this examination, It would be controversial dependent on the function of the products and the impact in our environment...
:biggrin:

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Yepp it was 1 mark,I put the C-C bonds can break anywhere coz there was a similar question in one of the past papers,saying why does cracking form a mixture of alkanes and alkenes,and that was the answer.

Reply 4122

Chrisd00100

Checked the unofficial mark scheme... I think I'll have at least 75 marks as I marked only the things I was sure of and left some stuff out... Hope I have some more marks and get myself an A, that would be awesome!

Biology and Chemistry, the 50% ones and also geology, went alright, I think at least B for both, if less than that, will be really disappointing....
The 50% exams which are supposed to be harder went better than the 30%'s lol

Reply 4123

V__005

Original post by Joew1995

Can you send me a link to the mark scheme please? :smile:

Reply 4124

MBee

for radical subsition i put
1)FREE radical substitution, is that okay with the 'free' ?
2) homolytic fission
3) would you get a mark for saying initiation and propagation with incorrect equations?
seems to be the question where ive lost the most marks :frown:

Reply 4125

Chrisd00100

Many people are saying it went realy well, I hope the grade boundaries don't go up!

In January 2012 it was 76 to get a B (I think recently 79 was an A) and 83 to get an A. I hope it satays at 79 or 80... Lower if possible :wink:

*fingers crossed*

Reply 4126

V__005

Original post by Matthewgj

It said essential conditions.

You may be right, but my reasoning would be behind that fermentation cannot occur unless you have the optimum temperature and the microbe present.

The book says that fermentation can happen anaerobically, however it isn't a necessary condition.

I put temperature of 37 degrees celcius and yeast (zymase)?

Reply 4127

TheFootyKing19

Original post by Varsh05

Can you send me a link to the mark scheme please? :smile:

http://www.thestudentroom.co.uk/attachment.php?attachmentid=223281&d=1370370378

UNOFFICIAL MS. There's probably 1/2 errors but yeah it seems all good.

Reply 4128

Matthewgj

Original post by Varsh05

I put temperature of 37 degrees celcius and yeast (zymase)?

Thats fine :smile:

Reply 4129

TheFootyKing19

Original post by Chrisd00100

*fingers crossed*

That Jan12 paper was ridiculously easy though

Don't worry it won't be higher than 80 for an A, I'm pretty certain of that.

Reply 4130

Chrisd00100

in propagation i wrote initially:

CH4 + Br* -> *CH3 + HBr
*CH3 + IBr -> CH3I + Br*

But then I deleted the second equation and wrote the same but it forming CH3Br and I*. As In IBr, Br is more electronegative, so it will have a negative delta... dunno if that's important or not lol... I hope they alo so...

Then made CH3I in the termination step, *CH3 + I* -> CH3I

Original post by TheFootyKing19

That Jan12 paper was ridiculously easy though

Don't worry it won't be higher than 80 for an A, I'm pretty certain of that.

Hope so xD I think I might have at least 72-75... Hope it's a 80+ xD
Good luck

(edited 10 years ago)

Reply 4131

Ché.

Original post by hassanakhtaruk

So by writing an incorrect thing (C-H) and a correct thing (C-C) ..it's not contradicting?

Remember?
In this case, it should be okay.
They do write in the notes that contradicting statements are ignored in a one-mark question.
I mean it is one mark, but that's not the point.
It's still a mark, 'ey!?

I think might need the worst random somewhere or breaks everywhere in the chain of molecule.
Have you notice they contain the sentence starter in brackets sometimes?
The main body isn't so if that's in context then you should be awarded the mark!

I hope you do now...
AWARD IT OCR!
:frown:

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Reply 4132

fluker6696

What would happen if I put the correct structures (i.e. ketone and aldehyde) but incorrectly named the aldehyde as butan-1-one (stupid, I know). They didn't ask us to name them, so would the marker just ignore it?

Reply 4133

Ché.

Original post by Chrisd00100

I have come to a (hopeful) valid conclusion that the larger the module, the more endurance you need.
I mean, Biology?
They had first unit material as questions so candidates round have noticed!
If you know a variety, you're totally good!

Good luck for your results from today!

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